I did this a couple years back and you really have to think about how you ride. I mean, if you've been riding for any amount of time, riding regular is going to be like instinct. So you have to break that down: balance, lean, positioning, how do you initiate turns, etc. Start breaking that in to pieces and work on it that way. (As an added bonus, re-"learning" how to ride switch was tremendously helpful when I had to teach my wife how to snowboard)
Riding switch isn't going to be automatic at first, so you're just going to have to commit to it.